3.4 What has any of this to do with computers?
Human beings invented computers because we have a compelling interest in data. We seek to turn our perceptions of sensations into symbols, and then to store, analyse, process, and turn these symbols into something else: information. Modern computers, with their enormous storage capacity and incredible processing power, are an ideal tool for doing this. They allow us to acquire data, code it in terms of signs, store, retrieve, or combine it with other data. Sophisticated output devices allow us to present the results of all this processing (i.e. information) in ways that were hitherto impossible, too time consuming, or too expensive.
Long before we developed computers, human beings began developing tools to enhance and extend our perceptions, to help us know better what sort of world we lived in. Telescopes extended our sense of vision by compressing distance for us. We can make temperature sensors to determine the temperature of things so hot or so cold (e.g. the temperature of a kiln or liquid nitrogen, respectively) that we cannot possibly sense these directly without severe harm to ourselves.
Likewise, humans have invented many devices to amplify their muscle power. For example, a hydraulic lift can perform hundreds of times the amount of work that a human or an animal can. Automobiles and jet aircraft enable us to move at speeds and cover distances that would be impossible if we had to depend on our own legs, or even those of an animal like a horse.
Remote sensing satellites have been examining the earth from space since the 1970s. They do so using not only the spectrum of light visible to our eyes but also infrared and ultraviolet radiation. The pictures built up through their sensing processes are decomposed into symbols which a digital computer can process. These symbols are stored, and then transmitted to an earth station where another computer converts the symbols back into pictures.
If temperature is sensed instead of light, a picture is built up using a technique called false colour, where colours are assigned to values of (in this case) temperature. Commonly, a so-called ‘cold’ dark colour, like black or deep blue, is assigned to areas of relatively low temperature, and a so-called ‘hot’ colour, like orange, to areas of higher temperature, with intermediate temperatures being represented by other colours.
In other examples, remote sensing is sensitive enough to detect disease or pests in crops before they are noticeable from the ground. It has also located upwellings of colder water in the seas and has resulted in the discovery of two hitherto unknown islands in the Arctic.
Figure 3 shows a false-colour image of a huge ice-storm system over eastern Canada.
Computers started as calculating instruments that took as input numbers symbolising things such as distance to a target and the velocity of a missile, and calculated ballistic trajectories to enable artillery troops to fire shells accurately. However, it quickly became obvious that computers could be used for far more than merely ‘number crunching’, because anything that can be symbolised in an appropriate code can be captured in a computer, stored, processed, and then fed back as information.
Using simple devices, computers can mimic our senses and gather data we have no way of dealing with directly. For example, photographs from space probes cannot come back to earth as rolls of film to be developed: they are transmitted back as radio signals which computers can reassemble into pictures. These pictures can be derived from things we cannot see, such as ultraviolet radiation.
The information that computers produce can be used to control devices like mechanical or hydraulic machinery. For example, computers can be ‘put in charge’ of machinery that might be dangerous for humans to operate, or which might move too fast for our nervous systems to control.
Furthermore, computers have vast memories, and they don't object to storing huge collections of data (e.g. all the tax records of individuals and firms in the UK) that are far beyond the capacity (or, indeed, interest) of a single human being. Once such data is stored, we do not need to remember it: rather we can concentrate on remembering what it describes and where it can be found.
List at least four ways in which computers are important to human activities. You should think of one or two that are not mentioned above.
You should have listed at least four items similar to the following.
Computers can store large amounts of data.
They are not bored by what people might consider to be trivia.
They can be used to control machinery in remote or dangerous situations or where things happen too quickly for human responses.
They are useful for data analysis.
They facilitate the transmission of data across vast distances by, for example, putting a picture into a form that can be transmitted, and then reassembling it into a picture at the receiving end.
The remainder of this course will provide some further discussion of the points raised so far and provide examples (called case studies) of how people have used computer systems as tools to process data and produce information.